Greening the greenhouse: general considerations Gerard Bot Wageningen UR Greenhouse Horticulture Greening the Greenhouse; April 2, 2008

Trends in European Horticulture Increase of scale partner in the market chain Greening the Greenhouse; April 2, 2008 Introduction Improved control crop growth factors production : quality + quantity Year round crop production: labour + market Sustainability: CPC, water, materials, energy bottleneck: energy consumption Licence to produce Licence to deliver

Energy consumption in European greenhouses 1900 MJm -2 (45 l oil m -2 ) 1500 MJm -2 (35 l oil m -2 ) 500 MJm -2 (12 l oil m -2 ) Greening the Greenhouse; April 2, 2008 Amsterdam

Greening the Greenhouse; April 2, 2008 Yield in European greenhouses

Introduction Greening the Greenhouse; April 2, 2008 objectives for Northern and Southern regions Year round: - maximize solar radiation (crop production!) - minimize energy consumption Hot periods: - energy efficient cooling to reduce high temperatures Of course grower needs: - profitable crop production

Greening the greenhouse: energy saving properties: low heat loss: greenhouse cover insulation control: climate settings and control strategy: temperature + humidity + CO 2 winter: heating and ventilation; summer: efficient cooling conversion of primary energy to heat: the engine of the greenhouse: boiler, cogeneration, heat pump, fuel cell, … combined with high light transmission: crop production + solar energy in From a systems point of view:

cover k-value (W/m 2 K) single glass5.7 Double or 1+screen3.0 triple or 2+screen2.3 HR++*1.6 Vacuum glas* k (W/m2K) Rel. Econs (%) boiler Properties: cover insulation and energy consumption Greening the Greenhouse; April 2, 2008

cover k-value (W/m 2 K) single glass5.7 Double or 1+screen3.0 triple or 2+screen2.3 HR++*1.6 Vacuum glas* k (W/m2K) Rel. Econs (%) boiler properties plus energy friendly control about 20 % improvement possible maintaining optimal crop production Greening the Greenhouse; April 2, 2008

heat-demand energy in: boiler Also changing the engine 100 heat demand energy in: work Heat Pump energy reservoir 100 COP= work (electricity) needs 60 primary energy so 40% energy saving Greening the Greenhouse; April 2, 2008

properties, control and other engine

Properties: Reduction of energy losses: insulation Decreasing k-value (W/m 2 K): Thermal screens Double or triple cover (glass, plastic film) Gas filled space between glass layers Vacuum space between glass layers Reduction of thermal radiation loss: Low TIR emission coatings Bottleneck: Light transmission Greening the Greenhouse; April 2, 2008

Properties: improved light transmission geometry of the material V structure: material Micro V: surface anti-reflection coating: +6% cleaning! Principle: multiple reflection increases light transmission 25 mm Lexan ZigZag TM Greening the Greenhouse; April 2, 2008

Energy friendly control aim: optimal crop production Greening the Greenhouse; April 2, 2008 grower holds the control-wheel estimated risks with humidity control crop dependent crop oriented research

Engine: heat pump and energy reservoir contains sufficient amount of energy in winter Greening the Greenhouse; April 2, 2008 to be filled in summer: exploiting excess solar energy Large capacity, 10 l oil eq per m 2 : 10 m 3 water/ m 2 with ΔT = 10K or 2000 kg PCM /m 2 Physically only possible in the soil: Aquifer or VSHE

emptying cold aquifer (greenhouse is cooled) filling warm aquifer 17 o C 7 o C heat exchanger Aquifer: Summer period: excess heat

Aquifer: Winter period 17 o C 7 o C heat pump heat exchanger emptying warm aquifer: greenhouse is heated filling cold aquifer

Seasonal storage Aquifer: 2 wells at different temperature specific geological conditions Vertical Soil Heat Exchanger: passive storage via boreholes not available at TLR Greening the Greenhouse; April 2, 2008

Generating electricity Electricity plant: 100% fuel energy in, 42% electric energy, useful 48% reject heat, lost By exploiting reject heat: 30% energy (CO 2 ) saving Bottleneck: centralised electr production greenhouses Holland 2000MW installed 40% of greenhouse area decentralise ep: local exploitation reject heat: Greening the Greenhouse; April 2, 2008

Conclusions Greenhouse horticulture is vigorous in N-W Europe Greening the Greenhouse; April 2, 2008 Energy is bottleneck in sustainability Energy saving via greenhouse properties, climate control and energy conversion

Conclusions Greening the Greenhouse; April 2, 2008 Greenhouse properties: - insulation - light transmission Climate control: interaction T and RH control growers tool to control production crop dependent: quantity and quality growers try to avoid risks (disease control) Energy conversion: - boiler with condensor - heat pump/seasonal storage - cogeneration

Thank you for your attention Greening the Greenhouse; April 2, 2008

Introduction Sustainable greenhouses Seasonal energy storage To be realised conclusions Greening the Greenhouse; April 2, 2008

Energy demand? demand for energy carriers like oil, gas, coal, etc?? in principle demand for - mechanical work, both at fixed locations and mobile - heat for processing and climate conditioning - lighting (included in mech work) - communication/info-tainment (same) Greening the Greenhouse; April 2, 2008

Demand for mechanical work versus heat? energy demand in various sectors MWUHU transport 20% (efficiency 25%) 5 - industry 40% (28% raw materials+heat>100 o C) 8 (electr) 4 domestic 20% 4 (electr)16 remainder 20% 7 (electr) 13 total excl transport 19 (electr)33 domestic ~ 20% transport ~ 20% industry ~ 40% remainder ~ 20% Estimation: Mech Work Units (MWU) and Heat Units (HU) First step to sustainability: energy saving Greening the Greenhouse; April 2, 2008

Generating electricity Electricity plant: 100% fuel energy in, 42% electric energy, usefull 48% reject heat, lost By exploiting reject heat: 30% energy (CO 2 ) saving Bottleneck: centralised el production greenhouses Holland 2000MW installed 40% of greenhouse area decentralise ep: local exploitation reject heat: 19 units electricity covers 19 units heat Greening the Greenhouse; April 2, 2008

Heat Pump:

Energy targets (Netherlands 2020: greenhouses without fossil fuel) target 2000 (50) target 2010 (35) 2020 target 2020 (0) Greening the Greenhouse; April 2, 2008